This will make it possible to log into a machine with SSH witout manual password authentication. This is often needed for non-interactive system tasks (like pushing files to an external host for backup purposes) as well as to avoid time consuming typing of LONG passwords.

Starting from OpenBSD4.7 a new packet filtering syntax is used. It is more generalized than before. This means that pf.conf needs to be translated to work properly. Typical use cases are NAT and port forwarding.

Sometimes the IP address of a net device needs to be determined programatically in cases the shell command ifconfig is not desirable. As an example, I wrote a small C program that updated the DNS records in the DNS provider’s database in the case of an IP address change.